Permanent magnet rotor

Abstract

The permanent magnet rotor is capable of making tolerance of attaching a magnet cover great, applying no stress to structural elements of the rotor, preventing the magnet cover from being damaged under an environment where thermal expansion and thermal contraction are repeated in response to temperature variation, and preventing scatter of magnets. The permanent magnet rotor of an inner rotor-type motor comprises: a rotor yoke; a plurality of permanent magnets being arranged on an outer circumferential face of the rotor yoke, the permanent magnets constituting a plurality of segments; and a ring-shaped magnet cover covering outer faces of the permanent magnets, the magnet cover being composed of a nonmagnetic material. An inner diameter of the magnet cover before covering the outer faces of the permanent magnets is smaller than an outer diameter of the circularly-arranged permanent magnets. At least one stretchable section, which is capable of being stretched in the circumferential direction, is formed in the magnet cover.

1 . A permanent magnet rotor of an inner rotor-type motor, comprising:
 a rotor yoke;   a plurality of permanent magnets being arranged on an outer circumferential face of the rotor yoke, the permanent magnets constituting a plurality of segments; and   a ring-shaped magnet cover covering outer faces of the permanent magnets, the magnet cover being composed of a nonmagnetic material,   wherein an inner diameter of the magnet cover before covering the outer faces of the permanent magnets is smaller than an outer diameter of the circularly-arranged permanent magnets, and   at least one stretchable section, which is capable of being stretched in the circumferential direction, is formed in the magnet cover.   
     
     
         2 . The permanent magnet rotor according to  claim 1 ,
 wherein the stretchable section is located at a position corresponding to a space between the adjacent permanent magnets, and   the stretchable section is bent to convex radially inward or outward.   
     
     
         3 . The permanent magnet rotor according to  claim 1 ,
 wherein at least a pair of the stretchable sections are axisymmetrically arranged.